Orly uses a system called DECOR to communicate Runway Visual Range (RVR) information to pilots. In poor weather conditions—such as the fog the airport experienced on Saturday—this system is essential. Last Saturday it stopped working, and the airport struggled to figure out why.

This use of ancient systems is apparently not unusual. Vice quotes Alexandre Fiacre, the secretary general of France's UNSA-IESSA air traffic controller union, as saying that "The tools used by Aéroports de Paris controllers run on four different operating systems, that are all between 10 and 20 years old," with Windows 3.1 being joined by Windows XP and unspecified UNIX systems. Fiacre says that the systems are poorly maintained as well. Moreover, the age of these systems means that it's hard to find staff who can work with them, with Fiacre explaining, "We are starting to lose the expertise [to deal] with that type of operating system. In Paris, we have only three specialists who can deal with DECOR-related issues." And this problem is getting worse as "One of them is retiring next year, and we haven't found anyone to replace him."

Le Canard Enchaîné writes that according to France's transport minister, airport systems will be upgraded by 2017. Fiacre, however, is unconvinced, saying it will be "2019 at the earliest, perhaps even in 2021."

Whenever the upgrade does happen, they might even switch to something made this century.